Light scanning device and image forming device

Title: Light scanning device and image forming device.Abstract: A light scanning device includes a movable section having a light reflecting section adapted to reflect light, oscillating around an oscillation axis, and having a variable magnitude of a maximum deflection angle of the oscillating, and a detection section adapted to detect the maximum deflection angle of the movable section, and the detection section includes a light source adapted to emit light to the light reflecting section, a light receiving section adapted to receive reflected light, which is the light emitted from the light source and then reflected by the light reflecting section, and a displacement driving section adapted to change a position of the light source in accordance with the maximum deflection angle of the movable section. ...

The present invention relates to a light scanning device and an image forming device.

2. Related Art

As a device of displaying a desired image (e.g., a commercial advertisement such as a commercial) on a screen, for example, there has been known a device, which is configured so as to respectively scan a laser beam emitted from a light source in horizontal and vertical directions of the screen using two galvanometer mirrors (see, e.g., JP-A-2003-131151). Further, in the device described in the related art document described above, the drive timing of each of the galvanometer mirrors is controlled by the detection signal of the optical sensor fixed on the screen. Further, it is also possible to obtain the maximum deflection angle of the galvanometer mirrors based on the detection signal of the optical sensor.

However, in the device described in the related art document described above, since the optical sensor is fixed with respect to the screen in the case of changing the size of the image on the screen by changing the maximum deflection angle of the galvanometer mirror, the detection accuracy of the optical sensor is apt to degrade depending on the level (in particular the case of a large deflection angle) of the maximum deflection angle of the galvanometer mirrors. In the case in which, for example, the maximum deflection angle is 40 degrees, and the optical sensor is disposed at the position where the optical sensor reacts the maximum deflection angle with the highest sensitivity, if the maximum deflection angle is changed to 80 degrees, the resolution of the deflection angle which can be detected by the optical sensor is degraded. As described above, according to the device described in the related art document described above, there arises a problem that the difference is caused in the detection accuracy of the maximum deflection angle, and it is unachievable to accurately detect the fact that the galvanometer mirror rotates (swings) at the maximum deflection angle to thereby control the galvanometer mirror.

SUMMARY

An advantage of some aspects of the invention is to provide a light scanning device and an image forming device capable of keeping the detection accuracy of the maximum deflection angle of a movable section even if the maximum deflection angle is changed.

Application Example 1

This application example is directed to a light scanning device including a movable section having a light reflecting section adapted to reflect light, oscillating around an oscillation axis, and having a variable magnitude of a maximum deflection angle of the oscillating, and a detection section adapted to detect the maximum deflection angle of the movable section, and the detection section includes a light source adapted to emit light to the light reflecting section, a light receiving section adapted to receive reflected light, which is the light emitted from the light source and then reflected by the light reflecting section, and a displacement driving section adapted to change a position of the light source in accordance with the maximum deflection angle of the movable section.

According to this application example, the light scanning device is provided with the movable section and the detection section. The movable section has the light reflecting section for reflecting the light, and is oscillated around the oscillation axis. Therefore, when irradiating the light reflecting section with the light, the light reflected by the light reflecting section is scanned. Further, the maximum deflection angle of the movable section is arranged to be variable. The detection section has the light source, the light receiving section, and the displacement driving section. Further, the light source emits the light to the light reflecting section, and the light receiving section receives the reflected light reflected by the light reflecting section. By the light receiving section receiving the reflected light, the detection section detects the maximum deflection angle of the movable section. When changing the magnitude of the maximum deflection angle of the rotation, the displacement driving section changes the position of the light source. Therefore, the position of the light source can be changed even when changing the maximum deflection angle of the movable section. Therefore, the detection accuracy of the maximum deflection angle can be kept even when changing the maximum deflection angle of the movable section.

Application Example 2

In the light scanning device according to the application example described above, it is preferable that assuming that the maximum deflection angle is θmax, and an angle formed by the light source, the oscillation axis of the movable section, and the light receiving section is 2θ0, the displacement driving section changes the position of the light source so that a ratio θmax/θ0 between θmax and θ0 becomes constant.

According to this configuration, the displacement driving section changes the position of the light source even when changing the maximum deflection angle of the movable section. Further, the ratio between a half of the angle formed by the light source, the oscillation axis of the movable section, and the light receiving section and the maximum deflection angle is set to a predetermined ratio. On this occasion, since the light receiving section can receive the reflected light at the maximum deflection angle, it is possible to surely keep the detection accuracy of the maximum deflection angle.

Application Example 3

In the light scanning device according to the application example described above, it is preferable that the ratio θmax/θ0 exceeds 1, and is one of equal to and lower than 1.3.

According to this configuration, the ratio θmax/θ0 is greater than 1 and no greater than 1.3. When the ratio θmax/θ0 is lower than 1, the maximum deflection angle θmax of the movable section is smaller than a half of the angle formed by the light source, the oscillation axis of the movable section, and the light receiving section, and therefore, the light receiving section fails to receive the reflected light. Further, when the ratio θmax/θ0 is equal to 1, the light receiving section can receive the light with the highest sensitivity. Further, when the ratio θmax/θ0 is higher than 1.3, the sensitivity in receiving light of the light receiving section is degraded. Therefore, when the ratio θmax/θ0 is in the range described above, the detection accuracy of the maximum deflection angle can surely be kept even if the maximum deflection angle of the movable section is changed.

Application Example 4

In the light scanning device according to the application example described above, it is preferable that the displacement driving section includes an electric motor, and a control section having a function of controlling an actuation of the electric motor, and the electric motor changes the position of the light source.

According to this configuration, the angle formed by the light source, the oscillation axis of the movable section, and the light receiving section can be determined due to the rotation of the electric motor. Further, by the control section controlling the actuation of the electric motor, the angle formed by the light source, the oscillation axis of the movable section, and the light receiving section is controlled. Therefore, it is possible to simplify the configuration of the displacement driving section.

Application Example 5

In the light scanning device according to the application example described above, it is preferable that there is further provided a support beam coupled to a drive shaft of the electric motor, and adapted to support the light source, and the drive shaft is disposed coaxially with the oscillation axis of the movable section.

According to this configuration, the support beam for supporting the light source is coupled to the drive shaft of the electric motor. Thus, it becomes possible to easily calculate the angle formed by the light source, the oscillation axis of the movable section, and the light receiving section based on the rotational angle of the drive shaft rotated by the electric motor. Therefore, the control when the displacement driving section displaces the light receiving section can easily be performed.

Application Example 6

In the light scanning device according to the application example described above, it is preferable that the displacement driving section makes a distance between the movable section and the light source constant.

According to this configuration, the light path length of the light emitted from the light source, then reflected by the light reflecting section of the movable section, and then reaching the light receiving section is kept constant. Therefore, the light receiving section can receive the reflected light with a stable light intensity.

Application Example 7

In the light scanning device according to the application example described above, it is preferable that the light receiving section is formed of a photodiode.

According to this configuration, the photodiode of the light receiving section flows the current with the intensity corresponding to the intensity of the light received. Then, it is possible to easily determine whether or not the light receiving section receives the light using the current.

Application Example 8

In the light scanning device according to the application example described above, it is preferable that the light source emits a laser beam.

According to this configuration, the light source emits the laser beam. The laser beam is the light having the optical characteristics superior in directionality, convergent property, high-intensity property, and so on. Therefore, it is possible to efficiently emit the laser beam toward the light reflecting section of the movable section.

Application Example 9

In the light scanning device according to the application example described above, it is preferable that the screen is irradiated with the light reflected by the light reflecting section, and the screen is scanned with the light in a predetermined direction.

According to this configuration, in the case of attempting to vary the size in a predetermined direction when irradiating the screen with the light, the change in size can surely be performed by making the magnitude of the maximum deflection angle variable.

Application Example 10

This application example is directed to an image forming device including the light scanning device described above, and the light reflecting section scans the light to form an image with the light.

According to this application example, the image forming device is provided with the light scanning device described above. Therefore, when changing the size of the image by changing the maximum deflection angle of the movable section, the maximum deflection angle can be detected with good accuracy. As a result, the image forming device equipped with the light scanning device capable of detecting the scanning width of the light with good quality can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.

FIG. 1 is a schematic diagram for explaining a configuration of a projector provided to an image forming device according to a first embodiment of the invention.

FIG. 2 is a schematic perspective view showing a light scanning device incorporated in the projector.

FIG. 3 is a schematic plan view for explaining an actuation state of the light scanning device.

FIG. 4 is a schematic plan view for explaining an actuation state of the light scanning device.

FIG. 5 is a schematic perspective view showing a structure of an image forming device according to a second embodiment of the invention.

FIG. 6 is a schematic diagram for explaining a configuration of a projector provided to the image forming device.

FIG. 7 is a schematic cross-sectional view showing a structure of a screen provided to the image forming device.

FIG. 8 is a graph showing a relationship between the transmittance of the screen and the level of the voltage applied to a liquid crystal polymer composite layer.

FIG. 9 is a schematic plan view for explaining an actuation state of the screen.

FIG. 10 is a schematic plan view for explaining an actuation state of the screen.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the light scanning device and the image forming device according to the invention will be explained in detail based on some exemplary embodiments shown in accompanying drawings. It should be noted that each of members in each of the drawings is illustrated with a different scale from each other in order for providing a size large enough to be recognized in the drawing.

First Embodiment

FIG. 1 is a schematic diagram for explaining a configuration of a projector provided to an image forming device according to a first embodiment. FIG. 2 is a schematic perspective view showing a light scanning device incorporated in the projector. FIGS. 3 and 4 are schematic plan views for explaining the actuation state of the light scanning device. It should be noted that the upper side of FIG. 2 is referred to as “up” or “above,” and the lower side is referred to as “down” or “below” for the sake of convenience of explanation.

As shown in FIG. 1, the image forming device 100 has a screen 600 as a display object located inside (indoor) of a building or outdoors, and a projector 700 for displaying a predetermined image such as a still image or a moving image on a display surface 600a formed on the front side of the screen 600.

The screen 600 is fixed to, for example, a wall of the building. The display surface 600a of the screen 600 has an impermeable property, and is an opaque white substance. Thus, the image can clearly be displayed with the display light LL″ emitted from the projector 700.

Further, the projector 700 is disposed in the vicinity of the screen 600, and is configured to display the image on the screen 600 using proximity projection.

Further, the projector 700 is disposed in a place on the lower side of and close to the screen 600. Further, the projector 700 is disposed within 1 m from the region of the display surface 600a of the screen 600 closest to the projector 700. By disposing the projector 700 in the vicinity of the screen 600 as described above, it is possible to effectively prevent the display light LL″ emitted from the projector 700 from being blocked by a barrier such as a pedestrian. Further, it is possible to more reliably display a desired image on the display surface 600a.

The projector 700 has a light source unit 200 (a light emitting section) for emitting the display light LL″, a light scanning device 1 (a light scanning section) for reflecting the display light LL″ emitted from the light source unit 200 to thereby scan the display surface 600a of the screen 600 with the display light LL″, and a control section 400 for controlling the actuation of the light source unit 200 and the light scanning device 1. Further, the light source unit 200 has a display light source 200b for emitting the display light LL″ for displaying the image on the display surface 600a.

The display light source 200b is provided with laser sources 210r, 210g, and 210b for respective colors of red, green, and blue, and collimator lenses 220r, 220g, and 220b and dichroic mirrors 230r, 230g, 230b disposed correspondingly to the laser sources 210r, 210g, and 210b of the respective colors. The laser sources 210r, 210g, and 210b of the respective colors emit laser beams RR, GG, and BB of red, green, and blue, respectively. The laser beams RR, GG, BB are respectively emitted in the condition of being modulated in accordance with a drive signal transmitted from the control section 400, and then collimated by the collimator lenses 220r, 220g, and 220b to be formed as fine beams.

The dichroic mirrors 230r, 230g, and 230b have properties of reflecting the red laser beam RR, the green laser beam GG, and the blue laser beam BB, respectively, and combine the laser beams RR, GG, and BB of the respective colors with each other to emit the unified display light LL″ (the laser beam).

It should be noted that a collimator mirror can be used instead of the collimator lenses 220r, 220g, 220b, and also in this case, the fine collimated light beams can be formed. Further, in the case in which the collimated light beams are emitted from the laser sources 210r, 210g, and 210b of the respective colors, the collimator lenses 220r, 220g, and 220b can be eliminated. Further, the laser sources 210r, 210g, and 210b can be replaced with light sources such as light emitting diodes for generating similar light beams.

Further, the order of the laser sources 210r, 210g, and 210b, the collimator lenses 220r, 220g, and 220b, and the dichroic mirrors 230r, 230g, and 230b of the respective colors is nothing more than an example. The order thereof can freely be set while keeping the combinations for the respective colors (the laser source 210r, the collimator lens 220r, and the dichroic mirror 230r for red, the laser source 210g, the collimator lens 220g, and the dichroic mirror 230g for green, and the laser source 210b, the collimator lens 220b, and the dichroic mirror 230b for blue). For example, the combination of blue, red, and green in the order from a light scanner 310 is also possible.

The light scanning device 1 has a function of emitting the display light LL″ emitted from the light source unit 200 to the screen 600 to thereby scan the display surface 600a with the display light LL″. Such a light scanning device 1 has a light scanner 310 as a horizontal scanning mirror for scanning the display surface 600a in a horizontal direction (an x direction) with the display light LL″ emitted from the light source unit 200. Further, the light scanning device 1 has a light scanner 330 as a vertical scanning mirror for scanning the display surface 600a in a vertical direction (a y direction) with the display light LL″ emitted from the light source unit 200, and an angle detection section 340 for detecting the rotational angle (behavior) of a movable plate 331a provided to the light scanner 330.

The movable plate (movable section) 311a is formed of a plate-like body. Further, the movable plate 311a is provided with a light reflecting section 311e (a mirror) having a light-reflecting property disposed on one surface thereof. Further, the movable plate 311a rotates (oscillates) around a rotational center axis (an oscillation axis) J1 perpendicular to the thickness direction thereof due to the electromagnetic drive using a magnet coil (not shown) and a permanent magnet (not shown). By the rotation of the movable plate 311a, it is possible to scan the screen 600 with the display light LL″ reflected by the light reflecting section 311e in the horizontal direction.

Further, by controlling the amplitude and the drive frequency of the voltage to be applied to the magnetic coil using the control section 400, it is possible to vary the magnitude of the maximum deflection angle (rotational angle) θmax of the movable plate 311a. For example, in the case of attempting to vary the size (the projection size) in the horizontal direction of the image on the screen 600, the variation can surely be performed by making the magnitude of the maximum deflection angle θmax variable. Here, the maximum deflection angle θmax denotes the maximum angle of the movable plate 311a in the horizontal direction shown in FIGS. 3 and 4 with respect to the normal line N in the initial state in which the movable plate 311a has not yet been actuated.

Incidentally, if the deflection angle of the movable plate 311a of the light scanner 310 is constant, the displacement of the display light LL″ in the light emitting state varies in accordance with the angle of the movable plate 331a of the light scanner 330, and increases as the position on the display surface 600a in the vertical direction scanned with the display light LL″ gets away from the projector 700. Therefore, in the projector 700, by arranging that the further from the projector 700 the position on the display surface 600a in the vertical direction is, the smaller the deflection angle of the movable plate 311a is, the displacement of the display light LL″ in the light emitting state is made constant along the vertical direction. By performing such a correction, so-called “keystone distortion” can be corrected.

The movable plate 331a is also formed of a plate-like body. Further, the movable plate 331a is provided with a light reflecting section 331e (a mirror) having a light-reflecting property disposed on one surface thereof. Further, the movable plate 331a is driven around a rotational center axis J2 having a perpendicular positional relationship with the rotational center axis J1 due to the electromagnetic drive using, for example, a magnetic coil (not shown) and a permanent magnet (not shown). By the rotation describe above, it is possible to scan the screen 600 with the display light LL″ reflected by the light reflecting section 331e in a perpendicular direction (the vertical direction). Further, by the scanning in the vertical direction and the scanning in the horizontal direction, it is possible to form the image on the screen 600.

Further, the control of the magnitude of the maximum deflection angle θmax of the movable plate 331a is performed by controlling the level of the voltage applied to the magnetic coil disposed so as to correspond to the movable plate 331a using the control section 400. The movable plate 311a (except the light reflecting section 311e) and the movable plate 331a (except the light reflecting section 331e) are each formed using, for example, silicon as a primary material. The light reflecting sections 311e, 331e are each formed of a metal thin film formed by, for example, vapor deposition.

The angle detection section 340 can be composed of, for example, a strain gauge for detecting the stress caused in the movable plate while the movable plate 331a is moving, a resistance variation detection section for detecting the resistance variation in the strain gauge in accordance with the stress variation of the movable plate, and an angle detection section for obtaining the angle of (detecting the behavior of) the corresponding movable plate based on the detection result of the resistance variation detection section.

The control section 400 is configured so as to control the actuation of the light source unit 200 and the light scanning device 1 so that the display light LL″ is emitted based on the image data to be displayed on the display surface 600a of the screen 600 transmitted from a computer or the like not shown. Thus, it is possible to more reliably display the desired image on the display surface 600a.

Incidentally, as shown in FIGS. 1 and 2, the light scanning device 1 is further provided with a rotation detection section 2 as a detection section for detecting that the movable plate 311a of the light scanner 310 rotates with the maximum deflection angle θmax. In the light scanning device 1, it is possible to assure that the movable plate 311a rotates with the maximum deflection angle θmax within a predetermined detection accuracy (the maximum deflection angle θmax±1 degree) due to the activation of the rotation detection section 2.

As shown in FIG. 2, the rotation detection section 2 is composed of a light source 21 for emitting a laser beam SS toward the light reflecting section 311e of the movable plate 311a, a light receiving section 22 for receiving the reflected light, which is the laser beam SS from the light source 21 reflected by the light reflecting section 311e, and a displacement driving section 23 for changing the position of the light source 21 in accordance with the maximum deflection angle θmax of the movable plate 311a. Further, the light source 21, the light receiving section 22, and the displacement driving section 23 are disposed outside the light path of the display light LL″ from the light source unit 200, namely the position where these sections are prevented from blocking the display light LL″, inside the light scanning device 1.

The light receiving section 22 is fixed to a housing (not shown) of, for example, the light scanning device 1. Further, the light source 21 is electrically connected to the control section 400. Thus, the control section 400 can perform the control of putting on and off the light source 21.

Such a light source 21 is arranged to be able to emit the laser beam SS. Since the laser beam SS is light having the optical characteristics superior in directionality, convergent property, high-intensity property, and so on, it is possible to reliably emit the laser beam SS toward the light reflecting section 311e of the movable plate 311a with efficiency. It should be noted that the device for emitting the laser beam SS is not particularly limited, but there can be cited, for example, a gas laser device such as a He—Ne laser, a solid-state laser device such as a Nd-YAG laser, and a semiconductor laser such as a GaAlAs laser as the device for emitting the laser beam SS.

The laser beam SS (the reflected light) reflected by the light reflecting section 311e of the movable plate 311a is received by the light receiving section 22. The light receiving section 22 is formed of a photodiode electrically connected to the control section 400. Thus, the light receiving section 22 is arranged to generate the electrical current with the intensity corresponding to the intensity of the laser beam SS received. Further, it is possible to make a determination on whether or not the light receiving section 22 receives the laser beam SS based on the magnitude relation between the level of the current and a predetermined determination value set previously compared with each other. It should be noted that the determination value is stored in the control section 400.

Incidentally, the case in which the light source is fixedly installed with respect to the rotational center axis J1 of the movable plate 311a, for example, will be explained. An installation angle of the light receiving section 22 is defined as the angle formed by the light source 21, the rotational center axis J1 of the movable plate 311a, and the light receiving section 22. In this case, if the maximum deflection angle θmax is set to an angle far greater than a half of the installation angle of the light receiving section 22, the place irradiated with the laser beam SS goes beyond the light receiving section 22, and therefore, the detection accuracy (resolution) of the light receiving section 22 is degraded. The maximum deflection angle θmax can be obtained using Formula I below.

t2/t1=(1/π)*arccos(θ0/θmax) (1)

It should be noted that in FIG. 3 the course of the rotation of the normal line of the light reflecting section 311e of the movable plate 311a starting from the line connecting the rotational center axis J1 of the movable plate 311a and the light receiving section 22 and then returning to the line after a stroke is defined as a first course 3. The symbol t1 denotes the time necessary for the normal line to lap the first course 3. In other words, the end of the range of the stroke of the normal line located on the light receiving section 22 side is defined as a first rotation limit 4, and the end thereof located on the light source 21 side is defined as a second rotation limit 5. Further, the normal line makes a stroke between the first rotation limit 4 and the second rotation limit 5. The time t1 corresponds to the reciprocation time (cycle time) for the normal line of the movable plate 311a to make a stroke between the first rotation limit 4 and the second rotation limit 5.

A course of the normal line of the light reflecting section 311e moving from the line 22a connecting the rotational center axis J1 and the light receiving section 22 to the first rotation limit 4 and then returning to the line 22a from the first rotation limit 4 is defined as a second course 6. The symbol t2 denotes the time necessary for the normal line to move along the second course 6.

In the case in which, for example, the maximum deflection angle θmax is 40 degrees, and the light source 21 is disposed at the position where the reaction to the maximum deflection angel θmax with the highest sensitivity is obtained, if the maximum deflection angle θmax is changed to 80 degrees, the second course 6 is elongated. Therefore, the detection accuracy (sensitivity) of the light receiving section 22 is degraded. As described above, in the case in which the light source 21 is fixedly installed, the difference in the detection accuracy of the light receiving section 22 occurs. Therefore, it is unachievable to assure that the movable plate 311a is rotating with the maximum deflection angle θmax.

Therefore, the light scanning device 1 is configured to prevent such a problem. Specifically, when the maximum deflection angle θmax varies, the light scanning device 1 moves the position of the light source in conjunction with the variation of the maximum deflection angle θmax. Specifically, the light scanning device 1 is configured to rotate the light source 21 around a rotational center axis J3 as much as a following angle θ0 (rotational angle) (see FIGS. 3 and 4). It should be noted that the rotational center axis J3 on which the light source 21 is rotated is disposed coaxially with the rotational center axis J1 of the movable plate 311a. As a mechanism of moving the position of the light source 21, there is disposed the displacement driving section 23. It should be noted that the following angle θ0 is also an angle corresponding to a half of the angle formed by the light source 21, the rotational center axis J1 of the movable plate 311a, and the light receiving section 22.

Further, as shown in FIG. 2, the displacement driving section 23 provided to the rotation detection section 2 is composed of an electric motor 24, a motor driver 28, a control section 400, an encoder 25, a support beam 26, and so on. Thus, the displacement driving section 23 can be composed of a small number of units, and therefore, it is possible to make the configuration of the displacement driving section 23 relatively simple.

The electric motor 24 is, for example, a servomotor having a shaft 241 as a drive shaft. The electric motor 24 is electrically connected to the control section 400 via the motor driver 28. The command related to the rotational conditions (the following angle θ0, the rotational speed, and so on) of the shaft 241 from the control section 400 is transmitted to the motor driver 28. The motor driver 28 controls the actuation of the motor 24 in accordance with the command.

Further, the encoder 25 is capable of detecting the following angle θ0 of the shaft 241 and so on. By feeding back the detection result to the control section 400, the actuation of the electric motor 24 can be controlled with accuracy.

As shown in FIGS. 2 through 4, the electric motor 24 is disposed so that the rotational center axis J3 of the shaft 241 is located coaxially with the rotational center axis J1 of the movable plate 311a. Thus, the control section 400 can easily perform the control of “keeping the ratio θmax/θ0 in a predetermined value” as described later.

The support beam 26 having an elongated shape is connected to the shaft 241 of the electric motor 24. The support beam 26 extends in a direction perpendicular to the shaft 241. The support beam 26 supports the light source 21 via a spacer 27 at the end of the support beam 26. Thus, when the shaft 241 rotates around the rotational center axis J3, it is also possible for the light source 21 to rotate around the rotational center axis J3.

The constituent material of the support beam 26 is not particularly limited providing the material has sufficient rigidity, and a variety of metal materials such as aluminum or stainless steel, and a variety of resin materials such as polypropylene can be used as the constituent material of the support beam 26. Further, by forming the support beam 26 with the relatively toughened material as described above, it is possible for the support beam 26 to keep the distance between the light source 21 and the movable plate 311a (the rotational center axis J1) in a predetermined distance. Thus, the light path length of the laser SS emitted from the light source 21, then reflected by the light reflecting section 311e of the movable plate 311a, and then reaching the light receiving section 22 can be kept in the predetermined distance irrespective of the magnitude of the following angle θ0. Therefore, the intensity of the laser beam SS received in the light receiving section 22 becomes also constant, and thus, the stable light reception becomes possible.

Then, the control (the actuation of the light scanning device 1) of the control section 400 when confirming that the movable plate 311a is rotating with the maximum deflection angle θmax even in the case in which the maximum deflection angle θmax varies will be explained with reference to FIGS. 3 and 4. Hereinafter, the state shown in FIG. 3 is referred to as a “first state,” and the state shown in FIG. 4 is referred to as a “second state.”

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